U.S. patent number 10,114,396 [Application Number 15/005,014] was granted by the patent office on 2018-10-30 for induction type power supply system and intruding metal detection method thereof.
This patent grant is currently assigned to Fu Da Tong Technology Co., Ltd.. The grantee listed for this patent is Fu Da Tong Technology Co., Ltd.. Invention is credited to Chi-Che Chan, Ming-Chiu Tsai.
United States Patent |
10,114,396 |
Tsai , et al. |
October 30, 2018 |
Induction type power supply system and intruding metal detection
method thereof
Abstract
A method used for an induction type power supply system, for
detecting whether an intruding metal exists in a power transmission
region of the induction type power supply system, includes
interrupting at least one driving signal of the induction type
power supply system to stop driving a supplying-end coil of the
induction type power supply system; detecting an attenuation status
of a coil signal on the supplying-end coil when driving of the
supplying-end coil is interrupted; and determining whether the
intruding metal exists in the power transmission region of the
induction type power supply system according to the attenuation
status of the coil signal.
Inventors: |
Tsai; Ming-Chiu (New Taipei,
TW), Chan; Chi-Che (New Taipei, TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
Fu Da Tong Technology Co., Ltd. |
New Taipei |
N/A |
TW |
|
|
Assignee: |
Fu Da Tong Technology Co., Ltd.
(New Taipei, TW)
|
Family
ID: |
55559780 |
Appl.
No.: |
15/005,014 |
Filed: |
January 25, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20160139618 A1 |
May 19, 2016 |
|
Foreign Application Priority Data
|
|
|
|
|
Oct 28, 2015 [TW] |
|
|
104135327 A |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G05F
1/66 (20130101) |
Current International
Class: |
G05D
5/00 (20060101); G05F 1/66 (20060101) |
Field of
Search: |
;700/292 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1142649 |
|
Feb 1997 |
|
CN |
|
1476535 |
|
Feb 2004 |
|
CN |
|
1930790 |
|
Mar 2007 |
|
CN |
|
101106388 |
|
Jan 2008 |
|
CN |
|
101834473 |
|
Sep 2010 |
|
CN |
|
101907730 |
|
Dec 2010 |
|
CN |
|
101924399 |
|
Dec 2010 |
|
CN |
|
101978571 |
|
Feb 2011 |
|
CN |
|
102055250 |
|
May 2011 |
|
CN |
|
102157991 |
|
Aug 2011 |
|
CN |
|
102474133 |
|
May 2012 |
|
CN |
|
102804619 |
|
Nov 2012 |
|
CN |
|
102904475 |
|
Jan 2013 |
|
CN |
|
103069689 |
|
Apr 2013 |
|
CN |
|
103248130 |
|
Aug 2013 |
|
CN |
|
103425169 |
|
Dec 2013 |
|
CN |
|
103457361 |
|
Dec 2013 |
|
CN |
|
103852665 |
|
Jun 2014 |
|
CN |
|
103975497 |
|
Aug 2014 |
|
CN |
|
104521151 |
|
Apr 2015 |
|
CN |
|
104685760 |
|
Jun 2015 |
|
CN |
|
104734370 |
|
Jun 2015 |
|
CN |
|
105049008 |
|
Nov 2015 |
|
CN |
|
105449875 |
|
Mar 2016 |
|
CN |
|
205105005 |
|
Mar 2016 |
|
CN |
|
2608419 |
|
Jun 2013 |
|
EP |
|
2 793 355 |
|
Oct 2014 |
|
EP |
|
200660909 |
|
Mar 2006 |
|
JP |
|
2008206305 |
|
Sep 2008 |
|
JP |
|
2010213414 |
|
Sep 2010 |
|
JP |
|
2013135518 |
|
Jul 2013 |
|
JP |
|
2014171371 |
|
Sep 2014 |
|
JP |
|
2017511117 |
|
Apr 2017 |
|
JP |
|
100650628 |
|
Nov 2006 |
|
KR |
|
201034334 |
|
Sep 2010 |
|
TW |
|
I389416 |
|
Mar 2013 |
|
TW |
|
I408861 |
|
Sep 2013 |
|
TW |
|
201414130 |
|
Apr 2014 |
|
TW |
|
201415752 |
|
Apr 2014 |
|
TW |
|
201440368 |
|
Oct 2014 |
|
TW |
|
I459676 |
|
Nov 2014 |
|
TW |
|
I472897 |
|
Feb 2015 |
|
TW |
|
I483509 |
|
May 2015 |
|
TW |
|
2013043974 |
|
Mar 2013 |
|
WO |
|
2015154086 |
|
Oct 2015 |
|
WO |
|
Other References
Yang, "A Multi-Coil Wireless Charging System with Parasitic Mental
Detection", Donghua University Master Dissertation, China Master's
Theses Full-text Database, Engineering Technology II, vol. 09, May
2014. cited by applicant.
|
Primary Examiner: Ho; Hoai V
Attorney, Agent or Firm: Hsu; Winston
Claims
What is claimed is:
1. A method used for an induction type power supply system, for
detecting whether an intruding metal exists in a power transmission
region of the induction type power supply system, the method
comprising: interrupting at least one driving signal of the
induction type power supply system to stop driving a supplying-end
coil of the induction type power supply system; detecting an
attenuation status of a coil signal on the supplying-end coil when
driving of the supplying-end coil is interrupted; and determining
whether the intruding metal exists in the power transmission region
of the induction type power supply system according to the
attenuation status of the coil signal; wherein the step of
determining whether the intruding metal exists in the power
transmission region of the induction type power supply system
according to the attenuation status of the coil signal comprises:
configuring a threshold voltage; calculating a number of peaks
reaching the threshold voltage in the coil signal after the at
least one driving signal is interrupted; and determining that the
intruding metal exists in the power transmission region of the
induction type power supply system when the number is smaller than
a threshold value.
2. The method of claim 1, wherein the step of determining whether
the intruding metal exists in the power transmission region of the
induction type power supply system according to the attenuation
status of the coil signal comprises: determining that the intruding
metal exists in the power transmission region of the induction type
power supply system when an attenuation speed of the coil signal is
greater than a threshold value.
3. The method of claim 1, wherein the step of calculating the
number of peaks reaching the threshold voltage in the coil signal
after the at least one driving signal is interrupted comprises:
enabling a counter when the at least one driving signal is
interrupted; detecting whether a peak of the coil signal reaches
the threshold voltage during an oscillation cycle of the coil
signal after enabling the counter; increasing the counter by one
when detecting that the peak of the coil signal reaches the
threshold voltage, and then detecting whether another peak of the
coil signal reaches the threshold voltage during a next oscillation
cycle of the coil signal; and obtaining a counting result of the
counter as the number of peaks reaching the threshold voltage in
the coil signal when detecting that there is a peak of the coil
signal failing to reach the threshold voltage.
4. A method used for an induction type power supply system, for
detecting whether an intruding metal exists in a power transmission
region of the induction type power supply system, the method
comprising: interrupting at least one driving signal of the
induction type power supply system to stop driving a supplying-end
coil of the induction type power supply system; detecting an
attenuation status of a coil signal on the supplying-end coil when
driving of the supplying-end coil is interrupted; and determining
whether the intruding metal exists in the power transmission region
of the induction type power supply system according to the
attenuation status of the coil signal, wherein the step of
determining whether the intruding metal exists in the power
transmission region of the induction type power supply system
according to the attenuation status of the coil signal comprises:
configuring a threshold voltage; measuring an attenuation period of
the coil signal after the at least one driving signal is
interrupted, wherein the attenuation period starts when the at
least one driving signal is interrupted and ends when there appears
a peak of the coil signal failing to reach the threshold voltage;
and determining that the intruding metal exists in the power
transmission region of the induction type power supply system when
the attenuation period is shorter than a threshold value.
5. The method of claim 4, wherein the step of measuring the
attenuation period of the coil signal after the at least one
driving signal is interrupted comprises: enabling a timer when the
at least one driving signal is interrupted; detecting whether a
peak of the coil signal reaches the threshold voltage during an
oscillation cycle of the coil signal after enabling the timer;
after detecting that the peak of the coil signal reaches the
threshold voltage, detecting whether another peak of the coil
signal reaches the threshold voltage during a next oscillation
cycle of the coil signal; and stopping the timer and obtaining a
timing result of the timer as the attenuation period of the coil
signal when detecting that there is a peak of the coil signal
failing to reach the threshold voltage.
6. A method used for an induction type power supply system, for
detecting whether an intruding metal exists in a power transmission
region of the induction type power supply system, the method
comprising: interrupting at least one driving signal of the
induction type power supply system to stop driving a supplying-end
coil of the induction type power supply system; detecting an
attenuation status of a coil signal on the supplying-end coil when
driving of the supplying-end coil is interrupted; and determining
whether the intruding metal exists in the power transmission region
of the induction type power supply system according to the
attenuation status of the coil signal, wherein the step of
determining whether the intruding metal exists in the power
transmission region of the induction type power supply system
according to the attenuation status of the coil signal comprises:
configuring a plurality of threshold voltages; obtaining an
attenuation pattern of the coil signal according to attenuation
periods of peaks of the coil signal respectively attenuating to the
plurality of threshold voltages; and determining whether the
intruding metal exists in the power transmission region of the
induction type power supply system and determining a type or size
of the intruding metal according to the attenuation pattern.
7. A method used for an induction type power supply system, for
detecting whether an intruding metal exists in a power transmission
region of the induction type power supply system, the method
comprising: interrupting at least one driving signal of the
induction type power supply system to stop driving a supplying-end
coil of the induction type power supply system; detecting an
attenuation status of a coil signal on the supplying-end coil when
driving of the supplying-end coil is interrupted; determining
whether the intruding metal exists in the power transmission region
of the induction type power supply system according to the
attenuation status of the coil signal; and starting the at least
one driving signal in a phase-shift manner after determining
whether the intruding metal exists in the power transmission region
of the induction type power supply system; wherein the step of
starting the at least one driving signal in the phase-shift manner
comprises: starting the at least one driving signal wherein a phase
of a first driving signal and a phase of a second driving signal
among the at least one driving signal are the same; and gradually
adjusting one or both of the phases of the first driving signal and
the second driving signal, until the phase of the first driving
signal and the phase of the second driving signal are opposite.
8. A method used for an induction type power supply system, for
detecting whether an intruding metal exists in a power transmission
region of the induction type power supply system, the method
comprising: interrupting at least one driving signal of the
induction type power supply system to stop driving a supplying-end
coil of the induction type power supply system; detecting an
attenuation status of a coil signal on the supplying-end coil when
driving of the supplying-end coil is interrupted; determining
whether the intruding metal exists in the power transmission region
of the induction type power supply system according to the
attenuation status of the coil signal; and detecting a peak voltage
of the coil signal and configuring at least one threshold voltage
according to the peak voltage, wherein the at least one threshold
voltage is used for determining whether the intruding metal exists
in the power transmission region of the induction type power supply
system; wherein the at least one threshold voltage is smaller than
the peak voltage.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method used for an induction
type power supply system, and more particularly, to a method
capable of detecting whether an intruding metal exists in a power
transmission region of an induction type power supply system.
2. Description of the Prior Art
In an induction type power supply system, a power supply device
applies a driver circuit to drive a supplying-end coil to generate
resonance, in order to send electromagnetic waves. A coil of the
power receiving device may receive the electromagnetic waves and
perform power conversion to generate DC power to be supplied for
the device in the power receiving end. In general, both sides of
the coil are capable of transmitting and receiving electromagnetic
waves; hence, a magnetic material is always disposed on the
non-induction side of the coil, allowing the electromagnetic energy
to be aggregated on the induction side. The magnetic material close
to the coil may enlarge the coil inductance, which further
increases the electromagnetic induction capability. In addition,
the electromagnetic energy exerted on a metal may heat the metal;
this principle is similar to an induction cooker. Therefore,
another function of the magnetic material is to isolate the
electromagnetic energy, in order to prevent the electromagnetic
energy from interfering the operations of the device behind the
coil, and also prevent the electromagnetic energy from heating
surrounding metals for safety.
The induction type power supply system includes a power supply
terminal and a power receiving terminal, where an induction coil is
included in each terminal for sending power energy and control
signals. The safety issue should be considered in this system.
However, a user may intentionally or unintentionally insert a metal
between these induction coils when using the induction type power
supply system. If an intruding metal appears during power
transmission, the electromagnetic energy generated by the coil may
rapidly heat the intruding metal and cause an accident such as
burning or exploding. Therefore, the industry pays much attention
to this safety issue, and related products should possess the
capability of detecting whether an intruding metal exists. When
there exists an intruding metal, power supply output should be cut
off for protection.
The prior art (U.S. Publication No. 2011/0196544 A1) provides a
method of detecting whether an intruding metal exists between the
power supply terminal and the power receiving terminal. This method
has been applied to the products on sale. However, the prior art
still possesses at least the following shortcomings:
First, the prior art calculates a power loss by measuring an output
power of the power supply terminal and an input power of the power
receiving terminal, and determines existence of the intruding metal
based on the calculated power loss and a predetermined threshold
value. If the power loss exceeds the threshold value, an intruding
metal is determined to exist. The maximum problem of the method is
in the configuration of the threshold value. If the threshold limit
is too strict, the system may wrongly determine that there is an
intruding metal under a normal operation; if the threshold limit is
too loose, the protection may not be triggered when some types of
intruding metals exist. For example, when a smaller intruding metal
such as a coin, key or paper clip exists in the power transmission
region of the power supply terminal, there may not appear an
evident power loss but the intruding metal may still be heated
significantly. Further, the configuration of the threshold value
should be determined by performing data analysis based on a large
number of physical samples; this consumes a lot of time and
efforts.
Second, in the induction type power supply system, the factors
affecting the power transmission loss between the power supply
terminal and the power receiving terminal are very complex. The
power loss may be affected by various events such as
functionalities of circuit elements, matching of the coil and the
magnetic material, relative distance and horizontal location
offsets of the coils in both terminals, and media characteristics
between the coils, e.g., metal paints on the coils. Since there are
numerous affecting factors, the power losses of the products due to
element offsets are different. Therefore, the threshold value
cannot be too severe, which results in a limited protection
effect.
Third, in the industry associated with the induction type power
supply system, the power supply terminal and power receiving
terminal of an induction type power supply system may be
manufactured by different manufacturers and/or in different periods
based on commercial circulation. The configuration of the above
threshold value is usually implemented in the power supply
terminal, but the related power setting should be adjusted for
various types of power receiving circuits. It is hard to fully
consider the characteristics of every type of power receiving
circuits, such that compatibility problems are unavoidable.
Fourth, a circuit for implementing power measurements should be
disposed in each of the power supply terminal and power receiving
terminal, and the related circuit cost is necessary. In order to
perform power measurements with high accuracy, the implementation
requires a more complex circuit and thus requires a higher cost.
The difficulty of the implementation is also higher.
Fifth, different power settings may possess different power losses.
For example, an induction type power supply system has an output
power equal to 5 watts (W). Assuming that its basic power loss
substantially ranges from 0.5 W to 1 W, the power loss generated by
the intruding metal may not be detected if the power loss is within
1 W. If the output power is increased to 50 W, the basic power loss
will significantly increase to a range between 5 W and 10 W with
the same circuit design. The power threshold for determining the
intruding metal should also be increased with the same ratio. In
such a condition, many types of intruding metals may not be
detected. For example, the power loss generated by a paper clip is
quite small, and is easily ignored by the conventional intruding
metal detection method, while the electromagnetic induction energy
received by the paper clip is still large enough to generate high
temperature and cause an accident. In other words, the conventional
intruding metal detection method is not feasible when the induction
type power supply system is supplying power, especially when the
supplied power is high.
Thus, there is a need to provide another method of detecting the
intruding metal, in order to improve the protection effects on the
induction type power supply system.
SUMMARY OF THE INVENTION
It is therefore an objective of the present invention to provide a
method of detecting whether an intruding metal exists in the power
transmission region of an induction type power supply system and
the induction type power supply system using the same, in order to
realize more effective intruding metal detection and further
enhance the protection effects on the induction type power supply
system.
The present invention discloses a method used for an induction type
power supply system, for detecting whether an intruding metal
exists in a power transmission region of the induction type power
supply system. The method comprises interrupting at least one
driving signal of the induction type power supply system to stop
driving a supplying-end coil of the induction type power supply
system; detecting an attenuation status of a coil signal on the
supplying-end coil when driving of the supplying-end coil is
interrupted; and determining whether the intruding metal exists in
the power transmission region of the induction type power supply
system according to the attenuation status of the coil signal.
The present invention further discloses an induction type power
supply system. The induction type power supply system comprises a
supplying-end module. The supplying-end module comprises a
supplying-end coil, a resonant capacitor, at least one power driver
unit and a supplying-end processor. The resonant capacitor, coupled
to the supplying-end coil, is used for performing resonance
together with the supplying-end coil. The at least one power driver
unit, coupled to the supplying-end coil and the resonant capacitor,
is used for sending at least one driving signal to the
supplying-end coil, in order to drive the supplying-end coil to
generate power. The supplying-end processor is used for receiving a
coil signal on the supplying-end coil and executing the following
steps: controlling the at least one power driver unit to interrupt
the at least one driving signal, to stop driving the supplying-end
coil; detecting an attenuation status of the coil signal when
driving of the supplying-end coil is interrupted; and determining
whether the intruding metal exists in the power transmission region
of the induction type power supply system according to the
attenuation status of the coil signal.
These and other objectives of the present invention will no doubt
become obvious to those of ordinary skill in the art after reading
the following detailed description of the preferred embodiment that
is illustrated in the various figures and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an induction type power supply
system according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of an intruding metal determination
process according to an embodiment of the present invention.
FIG. 3 is a waveform diagram of driving signals which drive the
supplying-end coil to let the coil signal to oscillate stably.
FIG. 4 is a waveform diagram of attenuating oscillation of the coil
signal when the driving signals are interrupted.
FIG. 5A is a waveform diagram of normal attenuation of the coil
signal when the driving signals are interrupted where there is no
intruding metal.
FIG. 5B and FIG. 5C are waveform diagrams of attenuation of the
coil signal when the driving signals are interrupted where an
intruding metal exists.
FIG. 6 is a schematic diagram of using a threshold voltage for
determining the attenuation speed of the coil signal according to
an embodiment of the present invention.
FIG. 7 is a schematic diagram of a detailed process of intruding
metal determination according to an embodiment of the present
invention.
FIG. 8 is a schematic diagram of another detailed process of
intruding metal determination according to an embodiment of the
present invention.
FIG. 9A is a waveform diagram of attenuation of the coil signal
without any intruding metal when the driving signals are
interrupted.
FIG. 9B is a waveform diagram of attenuation of the coil signal
with an existing intruding metal when the driving signals are
interrupted.
FIG. 10 is a waveform diagram of detecting the attenuation speed of
the coil signal by interrupting the driving signals according to an
embodiment of the present invention.
FIG. 11 is a schematic diagram of starting the driving signals in a
phase-shift manner according to an embodiment of the present
invention.
DETAILED DESCRIPTION
Please refer to FIG. 1, which is a schematic diagram of an
induction type power supply system 100 according to an embodiment
of the present invention. As shown in FIG. 1, the induction type
power supply system 100 includes a supplying-end module 1 and a
receiving-end module 2. The supplying-end module 1 receives power
from a power supply device 10. The supplying-end module 1 includes
a supplying-end coil 142 and a resonant capacitor 141. The
supplying-end coil 142 is used for delivering electromagnetic
energies to the receiving-end module 2 to supply power. The
resonant capacitor 141, coupled to the supplying-end coil 142, is
used for performing resonance together with the supplying-end coil
142. In addition, in the supplying-end module 1, a magnetic
conductor 143 composed of magnetic materials may be selectively
disposed, to enhance the electromagnetic induction capability of
the supplying-end coil 142 and also prevent electromagnetic
energies from affecting the back-end circuits. The supplying-end
module 1 further includes power driver units 121 and 122, a
supplying-end processor 11 and a voltage dividing circuit 130. The
power driver units 121 and 122, coupled to the supplying-end coil
142 and the resonant capacitor 141, are used for sending driving
signals D1 and D2 to the supplying-end coil 142, respectively. The
power driver units 121 and 122 may be controlled by a supplying-end
processor 11, for driving the supplying-end coil 142 to generate
and send power. When the power driver units 121 and 122 are both
active, full-bridge driving is performed. In one embodiment, only
one of the power driver units 121 and 122 is active, or only one of
the power driver units 121 or 122 is disposed, which leads to
half-bridge driving. The supplying-end processor 11 may receive a
coil signal C1 (i.e., the voltage signal between the supplying-end
coil 142 and the resonant capacitor 141) from the supplying-end
coil 142, and determine whether an intruding metal 3 exists in the
power transmission region of the induction type power supply system
100 according to the coil signal C1. The voltage dividing circuit
130, which includes voltage dividing resistors 131 and 132, may
attenuate the coil signal C1 on the supplying-end coil 142 and then
output the coil signal C1 to the supplying-end processor 11. In
some embodiments, if the tolerance voltage of the supplying-end
processor 11 is high enough, the voltage dividing circuit 130 may
not be applied and the supplying-end processor 11 may directly
receive the coil signal C1 from the supplying-end coil 142. Other
possible components or modules such as a signal analysis circuit,
power supply unit and display unit may be included or not according
to system requirements. These components are omitted without
affecting the illustrations of the present embodiments.
Please keep referring to FIG. 1. The receiving-end module 2
includes a receiving-end coil 242, which is used for receiving
power from the supplying-end coil 142. In the receiving-end module
2, a magnetic conductor 243 composed of magnetic materials may also
be selectively disposed, to enhance the electromagnetic induction
capability of the receiving-end coil 242 and also prevent
electromagnetic energies from affecting the back-end circuits. The
receiving-end coil 242 may send the received power to a load unit
21 in the back end. Other possible components or modules in the
receiving-end module 2 such as a regulator circuit, resonant
capacitor, rectification circuit, signal feedback circuit, and
receiving-end processor may be included or not according to system
requirements. These components are omitted without affecting the
illustrations of the present embodiments.
Different from the prior art where both of the power supply
terminal and power receiving terminal have to perform power
measurement to determine the intruding metal via power loss
detection, the present invention may determine whether there exists
an intruding metal in the power transmission region of the
supplying-end coil by interpreting the coil signal in the power
supply terminal only. Please refer to FIG. 2, which is a schematic
diagram of an intruding metal determination process 20 according to
an embodiment of the present invention. As shown in FIG. 2, the
intruding metal determination process 20 is used for a power supply
terminal of an induction type power supply system (e.g., the
supplying-end module 1 of the induction type power supply system
100 shown in FIG. 1) and includes the following steps:
Step 200: Start.
Step 202: Interrupt the driving signals D1 and D2 of the induction
type power supply system 100 to stop driving the supplying-end coil
142.
Step 204: Detect an attenuation status of the coil signal C1 on the
supplying-end coil 142 when driving of the supplying-end coil 142
is interrupted.
Step 206: Determine whether the intruding metal 3 exists in the
power transmission region of the induction type power supply system
100 according to the attenuation status of the coil signal C1.
Step 208: End.
According to the intruding metal determination process 20, in the
supplying-end module 1 of the induction type power supply system
100, the driving signals D1 and D2 may be interrupted for a while
during the driving process. At this moment, the power driver units
121 and 122 may stop driving the supplying-end coil 142 (Step 202).
In general, when the supplying-end coil 142 is driven normally, the
driving signals D1 and D2 outputted by the power driver units 121
and 122 are two rectangular waves opposite to each other. In such a
situation, the coil signal C1 on the supplying-end coil 142 may
appear to oscillate stably, as shown in FIG. 3. When the driving of
the supplying-end coil 142 is interrupted, the coil signal C1 may
keep oscillating and attenuate gradually due to energies remaining
between the supplying-end coil and the resonant capacitor. FIG. 4
illustrates a situation of attenuating oscillation of the coil
signal C1. When the driving signals D1 and D2 are interrupted, the
driving signals D1 and D2, which are rectangular waves originally,
stay in a higher voltage level and a lower voltage level,
respectively, and stop driving the supplying-end coil 142. At this
moment, the coil signal C1 may start to attenuate and keep
oscillating. Subsequently, the supplying-end processor 11 detects
the attenuation status of the coil signal C1 (Step 204), and
determines whether the intruding metal 3 exists in the power
transmission region of the induction type power supply system 100
according to the attenuation status of the coil signal C1 (Step
206). More specifically, the supplying-end processor 11 may
determine whether the intruding metal 3 exists in the power
transmission region of the induction type power supply system 100
according to the attenuation speed of the coil signal C1.
Please refer to FIG. 5A, FIG. 5B and FIG. 5C. FIG. 5A is a waveform
diagram of normal attenuation of the coil signal C1 when the
driving signals D1 and D2 are interrupted where there is no
intruding metal. FIG. 5B and FIG. 5C are waveform diagrams of
attenuation of the coil signal C1 when the driving signals D1 and
D2 are interrupted where an intruding metal exists. The waveforms
shown in FIGS. 5A-5C will be compared as follows. In FIG. 5A, the
coil signal C1 may attenuate slowly if there is no intruding metal
until the driving signals D1 and D2 are restarted, where the
attenuation speed depends on the damping coefficient of the coil.
As shown in FIG. 5B, the attenuation speed of the coil signal C1
may significantly increase when an intruding metal exists. That is,
the intruding metal may significantly increase the damping
coefficient of attenuation of the coil signal C1 while absorbing
the energy sent by the supplying-end coil 142, such that the
oscillation amplitude of the coil signal C1 shrinks rapidly. FIG.
5C illustrates a condition where the intruding metal is larger,
which results in more rapid attenuation on the coil signal C1.
According to the above characteristics, a threshold value may be
configured by the supplying-end processor 11 for determining the
attenuation speed of the coil signal C1. For example, when the
attenuation speed of the coil signal C1 is greater than the
threshold value, the supplying-end processor 11 may determine that
there is an intruding metal existing in the power transmission
region of the induction type power supply system 100, and thereby
perform power cut or other protective actions.
The above method of determining the attenuation speed of the coil
signal C1 may be realized via configuration of a threshold voltage.
Please refer to FIG. 6, which is a schematic diagram of using a
threshold voltage for determining the attenuation speed of the coil
signal C1 according to an embodiment of the present invention. As
shown in FIG. 6, a waveform A illustrates a normal attenuation of
the coil signal C1 peaks when there is no intruding metal, and a
waveform B illustrates an attenuation of the coil signal C1 peaks
when an intruding metal exists. The coil signal C1 starts to
attenuate at a time point t1. The supplying-end processor 11 may
configure a threshold voltage V_th smaller than the maximum voltage
of the coil signal C1. If the peak value of the coil signal C1
attenuates to the threshold voltage V_th after a time point t2, the
attenuation speed is slower and the supplying-end processor 11 may
determine that there is no intruding metal. If the peak value of
the coil signal C1 attenuates to the threshold voltage V_th before
the time point t2, the attenuation speed is faster and the
supplying-end processor 11 may determine that there exists an
intruding metal.
Please keep referring to FIG. 6 together with FIG. 1. The
supplying-end processor 11 includes a processing unit 111, a clock
generator 112, a voltage generator 113, a comparator 114 and a
voltage detector 115. The clock generator 112, coupled to the power
driver units 121 and 122, is used for controlling the power driver
units 121 and 122 to send the driving signals D1 and D2 or
interrupt the driving signals D1 and D2. The clock generator 112
may be a pulse width modulation (PWM) generator or other type of
clock generator, which outputs a clock signal to the power driver
units 121 and 122. The voltage detector 115 is used for detecting a
peak voltage of the coil signal C1 and sending the detected voltage
information to the processing unit 111. The voltage detector 115
may be an analog to digital converter (ADC), which converts an
analog voltage on the supplying-end coil 142 into digital voltage
information and outputs the voltage information to the processing
unit 111. The processing unit 111, coupled to the voltage detector
115, then configures the threshold voltage V_th according to the
peak voltage information, and outputs the information of the
threshold voltage V_th to the voltage generator 113. Therefore, the
threshold voltage V_th may be used for determining whether an
intruding metal 3 exists in the power transmission region of the
induction type power supply system 100. The voltage generator 113
is used for outputting the threshold voltage V_th. The voltage
generator 113 may be a digital to analog converter (DAC), which
receives the threshold voltage information from the processing unit
111 and converts the information into an analog voltage to be
outputted. An input terminal of the comparator 114 may receive the
threshold voltage V_th, and another input terminal of the
comparator 114 may receive the coil signal C1 from the
supplying-end coil 142, so that the comparator 114 may compare the
coil signal C1 with the threshold voltage V_th to generate a
comparison result. The processing unit 111 then determines the
attenuation speed of the coil signal C1 according to the comparison
result, in order to determine whether there is an intruding metal
existing in the power transmission region of the induction type
power supply system 100. In other words, the present invention may
determine whether an intruding metal exists in the power
transmission region of the induction type power supply system 100
by obtaining the duration time of the peak voltage of the coil
signal C1 attenuating to the threshold voltage V_th.
In an embodiment, the supplying-end processor 11 may determine the
attenuation speed of the coil signal C1 according to the number of
peaks reaching the threshold voltage V_th in the coil signal C1
after the driving signals D1 and D2 are interrupted. Please refer
to FIG. 7, which is a schematic diagram of a detailed process 70 of
intruding metal determination according to an embodiment of the
present invention. As shown in FIG. 7, the detailed process 70,
which may be realized by the supplying-end processor 11 to
determine the attenuation speed of the coil signal C1 via the
number of peaks reaching the threshold voltage V_th, includes the
following steps:
Step 700: Start.
Step 702: Configure the threshold voltage V_th.
Step 704: Enable a counter when the driving signals D1 and D2 are
interrupted.
Step 706: Detect whether a peak of the coil signal C1 reaches the
threshold voltage V_th during an oscillation cycle of the coil
signal C1. If yes, go to Step 708; otherwise, go to Step 710.
Step 708: Increase the counter by one and enter the next
oscillation cycle. Then go to Step 706.
Step 710: Obtain a counting result of the counter, and the counting
result refers to the number of peaks reaching the threshold voltage
V_th in the coil signal C1.
Step 712: Determine whether the number of peaks reaching the
threshold voltage V_th in the coil signal C1 is smaller than a
threshold value. If yes, go to Step 714; otherwise, go to Step
716.
Step 714: Determine that there is an intruding metal existing in
the power transmission region of the induction type power supply
system 100.
Step 716: Determine that there is no intruding metal in the power
transmission region of the induction type power supply system
100.
Step 718: End.
According to the detailed process 70 of intruding metal
determination, the supplying-end processor 11 may configure the
value of the threshold voltage V_th. For example, the processing
unit 111 of the supplying-end processor 11 may configure the value
of the threshold voltage V_th according to the voltage information
from the voltage detector 115. Subsequently, when the driving
signals D1 and D2 are interrupted, the supplying-end processor 11
may enable a counter and start to detect the peak values of the
coil signal C1. The supplying-end processor 11 may detect the peak
value of the coil signal C1 during each oscillation cycle of the
coil signal C1. When the peak value still exceeds the threshold
voltage V_th, the supplying-end processor 11 will detect the
magnitude of the peak value in the next oscillation cycle and
increase the counter by one. With the peak attenuation of the coil
signal C1, the peak value may gradually fall to the threshold
voltage V_th. Until a peak smaller than the threshold voltage V_th
occurs, the supplying-end processor 11 may obtain the counting
result of the counter. This counting result refers to the number of
peaks reaching the threshold voltage V_th in the coil signal
C1.
In such a situation, the supplying-end processor 11 may determine
the attenuation speed of the coil signal C1 via the number of peaks
reaching the threshold voltage V_th in the coil signal C1. The more
the number of peaks reaching the threshold voltage V_th in the coil
signal C1, the slower the attenuation speed of the coil signal C1,
which means that the intruding metal may not exist. The fewer the
number of peaks reaching the threshold voltage V_th in the coil
signal C1, the faster the attenuation speed of the coil signal C1,
which means that there may be an intruding metal existing in the
power transmission region of the induction type power supply system
100. The supplying-end processor 11 may configure a threshold
value. If the number of peaks reaching the threshold voltage V_th
in the coil signal C1 is smaller than the threshold value, the
supplying-end processor 11 may determine that there is an intruding
metal in the power transmission region of the induction type power
supply system 100, and thereby perform power cut or other
protective actions. In contrast, if the number of peaks reaching
the threshold voltage V_th in the coil signal C1 is greater than
the threshold value, the supplying-end processor 11 may determine
that there is no intruding metal in the power transmission region
of the induction type power supply system 100.
In another embodiment, the supplying-end processor 11 may determine
the attenuation speed of the coil signal C1 according to an
attenuation period of the coil signal C1 after the driving signals
D1 and D2 are interrupted. Please refer to FIG. 8, which is a
schematic diagram of another detailed process 80 of intruding metal
determination according to an embodiment of the present invention.
As shown in FIG. 8, the detailed process 80, which may be realized
by the supplying-end processor 11 to determine the attenuation
speed of the coil signal C1 via the attenuation period of the coil
signal C1, includes the following steps:
Step 800: Start.
Step 802: Configure the threshold voltage V_th.
Step 804: Enable a timer when the driving signals D1 and D2 are
interrupted.
Step 806: Detect whether a peak of the coil signal C1 reaches the
threshold voltage V_th during an oscillation cycle of the coil
signal C1. If yes, go to Step 808; otherwise, go to Step 810.
Step 808: Enter the next oscillation cycle. Then go to Step
806.
Step 810: Stop the timer and obtain a timing result of the timer,
and the timing result refers to the attenuation period of the coil
signal C1.
Step 812: Determine whether the attenuation period of the coil
signal C1 is shorter than a threshold value. If yes, go to Step
814; otherwise, go to Step 816.
Step 814: Determine that there is an intruding metal existing in
the power transmission region of the induction type power supply
system 100.
Step 816: Determine that there is no intruding metal in the power
transmission region of the induction type power supply system
100.
Step 818: End.
According to the detailed process 80 of intruding metal
determination, the supplying-end processor 11 may configure the
value of the threshold voltage V_th. Similarly, the processing unit
111 of the supplying-end processor 11 may configure the value of
the threshold voltage V_th according to the voltage information
from the voltage detector 115. When the driving signals D1 and D2
are interrupted, the supplying-end processor 11 may enable a timer
and start to detect the peak values of the coil signal C1. The
supplying-end processor 11 may detect the peak value of the coil
signal C1 during each oscillation cycle of the coil signal C1. When
the peak value still exceeds the threshold voltage V_th, the
supplying-end processor 11 will detect the magnitude of the peak
value in the next oscillation cycle. With the peak attenuation of
the coil signal C1, the peak value may gradually fall to the
threshold voltage V_th. Until a peak smaller than the threshold
voltage V_th occurs, the supplying-end processor 11 may stop the
timer and obtain the timing result of the timer. This timing result
refers to the attenuation period of the coil signal C1 attenuating
to the threshold voltage V_th. In other words, the attenuation
period of the coil signal C1 starts when the driving signals D1 and
D2 are interrupted and ends when there appears a peak of the coil
signal C1 failing to reach the threshold voltage V_th.
In such a situation, the supplying-end processor 11 may determine
the attenuation speed of the coil signal C1 via the attenuation
period required by the peak value of the coil signal C1 to reach
the threshold voltage V_th. The longer the time period for the peak
value of the coil signal C1 to reach the threshold voltage V_th,
the slower the attenuation speed of the coil signal C1, which means
that the intruding metal may not exist. The shorter the time period
for the peak value of the coil signal C1 to reach the threshold
voltage V_th, the faster the attenuation speed of the coil signal
C1, which means that there may be an intruding metal existing in
the power transmission region of the induction type power supply
system 100. The supplying-end processor 11 may configure a
threshold value. If the attenuation period of the coil signal C1 is
shorter than the threshold value V_th, the supplying-end processor
11 may determine that there is an intruding metal in the power
transmission region of the induction type power supply system 100,
and thereby perform power cut or other protective actions. In
contrast, if the attenuation period of the coil signal C1 is longer
than the threshold voltage V_th, the supplying-end processor 11 may
determine that there is no intruding metal in the power
transmission region of the induction type power supply system
100.
Please note that the above method of determining the intruding
metal via the attenuation speed of the coil signal C1 is difficult
to be affected by the load in the power receiving terminal. That
is, even when the supplying-end module 1 is supplying power, the
intruding metal detection can still be performed by shortly
interrupting the driving signals D1 and D2. The load of the power
receiving terminal may not vary the attenuation status and speed of
the coil signal C1. Please refer to FIG. 9A and FIG. 9B, which
illustrate the situations where the power receiving terminal has a
load. As shown in the waveform of the coil signal C1, the
supplying-end coil 142 receives a feedback signal from the power
receiving terminal. FIG. 9A is a waveform diagram of attenuation of
the coil signal C1 without any intruding metal when the driving
signals D1 and D2 are interrupted. FIG. 9B is a waveform diagram of
attenuation of the coil signal C1 with an existing intruding metal
when the driving signals D1 and D2 are interrupted. As can be seen
from FIG. 9A and FIG. 9B, even if the supplying-end module 1 is
supplying power, the supplying-end processor 11 may still detect
evident variation in the attenuation speed of the coil signal C1
due to an existing intruding metal when the driving signals D1 and
D2 are interrupted. The attenuation speed will not be affected by
whether the power supply terminal is supplying power. In addition,
the attenuation speed of the coil signal C1 may not be affected
even when the output power of the supplying-end coil 142 is
enlarged. Please note that when the power receiving terminal has a
load, the amplitude of the coil signal C1 may vary during the
driving process. In such a situation, the voltage detector 115 may
immediately obtain the peak voltage of the coil signal C1, so that
the supplying-end processor 11 may adjust the threshold voltage
V_th according to the magnitude of the peak voltage received by the
voltage detector 115, in order to accurately detect the attenuation
speed of the coil signal C1. More specifically, the supplying-end
processor 11 may configure the threshold voltage V_th to be smaller
than the peak voltage of the supplying-end coil 142 under normal
driving, allowing the threshold voltage V_th to be used for the
detection of signal attenuation.
In addition, the method of detecting the attenuation speed of the
coil signal C1 by interrupting the driving signals D1 and D2 only
needs to perform interruption for a very short time during the
power output process, and should not affect power transmission.
Please refer to FIG. 10, which is a waveform diagram of detecting
the attenuation speed of the coil signal C1 by interrupting the
driving signals D1 and D2 according to an embodiment of the present
invention. As shown in FIG. 10, V1 stands for an output voltage
outputted to the load by the induction type power supply system
100. Since the power receiving terminal always possesses a large
regulation capacitor, the influence on the output voltage V1 due to
the short-term interruption of the driving signals D1 and D2 will
be quite small.
Please note that, in addition to detecting the attenuation speed of
the coil signal C1 to determine whether an intruding metal exists,
the supplying-end processor 11 may further determine the type or
size of the intruding metal. In an embodiment, the supplying-end
processor 11 may configure a plurality of threshold voltages and
obtain the attenuation pattern of the coil signal C1 according to
the attenuation periods of peaks of the coil signal C1 respectively
attenuating to the plurality of threshold voltages. Subsequently,
the supplying-end processor 11 may determine whether an intruding
metal exists in the power transmission region of the induction type
power supply system 100 and also determine the type or size of the
intruding metal according to the attenuation pattern of the coil
signal C1. For example, when two threshold voltages V_th1 and V_th2
are configured, the supplying-end processor 11 may obtain the
attenuation periods of the peaks of the coil signal C1 attenuating
to the threshold voltage V_th1 (or the number of peaks exceeding
the threshold voltage V_th1), and also obtain the attenuation
periods of peaks of the coil signal C1 attenuating to the threshold
voltage V_th2 (or the number of peaks exceeding the threshold
voltage V_th2). The supplying-end processor 11 may calculate the
attenuation slope of the coil signal C1 accordingly, in order to
determine the size or type of the intruding metal. Different types
of metals may appear to have different attenuation patterns. For
example, iron or copper may result in faster attenuation, so the
measured attenuation slope of the coil signal C1 is larger. In
contrast, aluminum may result in a relatively slow attenuation. In
addition, the intruding metal having a larger size may also
generate a larger slope. According to the determination of various
types of intruding metals, the system may perform appropriate
protective actions according to the level of threats possibly
generated by different types of intruding metals.
In this case, the supplying-end processor 11 may include two
voltage generators and two comparators, wherein the two voltage
generators output the threshold voltages V_th1 and V_th2,
respectively, and the two comparators correspondingly compare the
coil signal C1 with the threshold voltages V_th1 and V_th2,
respectively. The manufacturer of the induction type power supply
system 100 may dispose any number of voltage generators and
comparators in the supplying-end processor 11 according to
practical requirements, in order to determine the size or type of
intruding metal via any number of threshold voltages.
Please note that after the driving signals D1 and D2 are
interrupted and whether there is an intruding metal in the power
transmission region of the induction type power supply system 100
is determined, the driving signals D1 and D2 may restart in a
phase-shift manner, in order to prevent circuit components from
being burnt out due to instant and significant rising of the
amplitude of the coil signal C1. Please refer to FIG. 11, which is
a schematic diagram of starting the driving signals D1 and D2 in
the phase-shift manner according to an embodiment of the present
invention. As shown in FIG. 11, the driving signals D1 and D2 stay
on the high voltage level and low voltage level, respectively, when
interrupted. When the driving signals D1 and D2 restart, the
driving signal D1 is switched to the low voltage level, and then
the driving signals D1 and D2 are switched to the high voltage
level simultaneously. At this moment, the driving signals D1 and D2
are in the same phase, which may not generate resonant effects;
hence, the amplitude of the coil signal C1 may not rise
significantly. Subsequently, the clock generator 112 gradually
adjusts any one or both of the phases of the driving signals D1 and
D2, until the phase of the driving signal D1 and the phase of the
driving signal D2 become opposite. For example, the clock generator
112 may fine tune the time points of switching the driving signals
D1 or D2, allowing these two driving signals D1 or D2 to reach
opposite phases gradually. After the phase adjustment starts, the
driving capability of the driving signals D1 and D2 may increase
gradually, so that the driving effects realized by the resonant
circuit of the supplying-end coil 142 may be enhanced gradually.
This increases the amplitude of the coil signal C1. As a result,
the phase-shift manner may prevent the circuit components from
being burnt out due to instant and significant rising of the
amplitude of the coil signal C1.
As can be seen from the above descriptions, the present invention
can determine whether there is an intruding metal in the power
transmission region of an induction type power supply system, which
may be realized by detecting the status of the coil signal
attenuation. Those skilled in the art can make modifications and
alternations accordingly. For example, the structure of the
supplying-end processor 11 shown in FIG. 1 is only one of various
implementations. In practice, the modules such as the clock
generator 112, the voltage generator 113, the comparator 114 and
the voltage detector 115 may be included in the supplying-end
processor 11, or may be respectively disposed in the supplying-end
module 1. The implementations of each module should not be limited
to the scope described in this disclosure. As mentioned above, the
supplying-end module 1 may include any number of voltage generators
and comparators according to requirements of sensing the intruding
metal. For example, if a sensing requirement is to determine the
existence of the intruding metal only, one voltage generator and
one comparator are enough to meet this requirement. If a sensing
requirement needs to determine the size or type of the intruding
metal, multiple voltage generators and comparators may be disposed
to perform the determination. Multiple voltage generators and
comparators may also be used for enhancing the accuracy of the
determination. In addition, in the above embodiments, the two
driving signals D1 and D2 stay in different voltage levels when the
driving of coil is interrupted, but in another embodiment, the two
driving signals D1 and D2 may both stay in the high voltage level
or the low voltage level when the driving of coil is interrupted;
this is not limited herein. Furthermore, the above embodiments aim
at detecting the attenuation speed of the coil signals to determine
whether there is an intruding metal. In practice, instead of
detecting the attenuation speed, the embodiments of the present
invention may also determine the intruding metal by detecting other
attenuation characteristics such as the falling slope of peak
values or attenuation acceleration. In an embodiment, the
supplying-end processor 11 may also include a memory, for storing
the attenuation pattern of various intruding metals to be used for
comparison and matching with the detected attenuation pattern.
Please note that, even if the intruding metal is very small, the
intruding metal may still affect the attenuation status of the coil
signal when the driving of coil is interrupted as long as the
intruding metal enters the power transmission region of the
induction type power supply system. Therefore, the present
invention may detect a tiny intruding metal such as a coin, key or
paper clip. In addition, even when the output power varies, the
same intruding metal may still result in signal attenuation with
similar pattern and similar speed. In such a condition, the
intruding metal detection method of the present invention can be
applied to an induction type power supply system having any output
power values. Therefore, the increase in power value setting of the
induction type power supply system will not be limited due to the
problem where the threshold value of power loss for the intruding
metal detection is not easily determined as in the prior art. In
addition, the intruding metal detection method of the present
invention can be realized in the power supply terminal only, and
can be adapted to any receiving-end modules manufactured by
different manufacturers; that is, the intruding metal detection
method of the present invention implemented in the power supply
terminal has no compatibility problems with the power receiving
terminal. Furthermore, the coil signal attenuation due to
interruption on the driving of coil signal is not easily affected
by receiving-end loads, output power magnitudes and/or other
interferences, and the corresponding threshold value may be
accurately configured, allowing the existence of tiny intruding
metals to be effectively determined. Another benefit of the present
invention includes that, the intruding metal detection method can
only be realized by software control in the supplying-end
processor, where no additional hardware circuit is required. The
circuit costs can thereby be under control.
To sum up, the present invention may determine whether an intruding
metal exists in the power transmission region of an induction type
power supply system by detecting an attenuation status of the coil
signal on the supplying-end coil. In order to achieve an accurate
intruding metal detection, the driving signal may be interrupted to
stop driving the supplying-end coil during coil driving operations.
The attenuation status of the coil signal may be detected when the
driving is interrupted, and whether an intruding metal exists can
thereby be determined. As a result, the intruding metal detection
method with higher accuracy can be realized; this enhances the
protection effects on the induction type power supply system. In
addition, tiny intruding metals may also be detected according to
the intruding metal detection method of the present invention.
Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *